Fiber optic cassette, system, and method

ABSTRACT

A fiber optic cassette including a body defining a front and an opposite rear and an enclosed interior. A cable entry location is defined in the body for a cable to enter the interior of the cassette. The cable which enters at the cable entry location is attached to the cassette body and the fibers are extended into the cassette body and form terminations at connectors. The connectors are connected to adapters located at the front of the cassette. A front side of the adapters defines termination locations for cables to be connected to the fibers connected at the rear of the adapters. A cable including a jacket, a strength member, and fibers enters the cassette. The strength member is crimped to a crimp tube and is mounted to the cassette body, allowing the fibers to extend past the crimp tube into the interior of the cassette body. A strain relief boot is provided at the cable entry location.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/544,987, filed Oct. 7, 2011, which applicationis hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

As demand for telecommunications increases, fiber optic networks arebeing extended in more and more areas. Management of the cables, ease ofinstallation, and case of accessibility for later management areimportant concerns. As a result, there is a need for fiber optic devicesand methods which address these and other concerns.

SUMMARY

An aspect of the present disclosure relates to a fiber optic cassetteincluding a body defining a front and an opposite rear and an enclosedinterior. A cable entry location is defined in the body for a cable toenter the interior of the cassette. The cable which enters at the cableentry location is attached to the cassette body and the fibers areextended into the cassette body and form terminations at connectors. Theconnectors are connected to adapters located at the front of thecassette. A front side of the adapters defines termination locations forcables to be connected to the fibers connected at the rear of theadapters.

One aspect of the invention relates to providing a cable including ajacket, a strength member. The strength member and the jacket arecrimped to a crimp tube and is mounted to the cassette body, allowingthe fibers to extend past the crimped tube into the interior of thecassette body. A strain relief boot is provided at the cable entrylocation.

In one embodiment, the cable entry location is located at the rear ofthe cassette body opposite to the front. In one embodiment, the cassettebody defines a top surface and a bottom surface which define major sidesof the cassette body and extend between the front and the rear. Theadapters along the front are arranged linearly in one embodiment andextend in a longitudinal direction parallel to the major surfacesdefined by the top and the bottom of the cassette body. The cassette canbe oriented in any position, so that the top and bottom sides can bereversed, or positioned vertically, or at some other orientation.

In one embodiment, the cable at the cable entry location extendsparallel to the longitudinal direction before entry into the cassettebody.

Disposed within the cassette body are cable radius limiters whichprovide cable management of the fibers extending from the cable entrylocation to the connectors at the rear of the adapters.

In one embodiment, an adapter block with a plurality of adapters isformed and includes a front end, a rear end, and internal structureswhich allow mating with fiber optic connectors at the front end, such asSC or LC style connectors. The adapter block may be removable from aremainder of the cassette.

In one embodiment, a rear of the adapter block defines a rear clip whichretains a split sleeve and a hub and ferrule of a connector whichterminates an interior fiber. In another embodiment, the rear end of theadapter block defines an opening for receipt of an SC or LC styleconnector.

The cassette can be utilized in a chassis which includes a stationarymount relative to the chassis, or the cassette can be movably mounted,such as in a variety of sliding movements to allow access to a selectedcassette, thereby improving access to a selected front connectorattached to the cassette.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of a fiber opticcassette in accordance with the present invention;

FIG. 2 is a further perspective view of FIG. 1 with a portion of thebody removed to expose an interior of the cassette.

FIG. 3 is a top view of the cassette view of FIG. 2;

FIG. 4 is a schematic view of a portion of a fiber optic cable;

FIG. 5 is a schematic view of a crimp tube and crimp ring used forcrimping to a cable of FIG. 4.

FIG. 6 is an exploded view showing a rear of the adapter block includinga front portion for mating with an SC connector, and a rear portionwhich mates with a rear connector including a hub and ferrule.

FIG. 7 shows a perspective view of the adapter block of the cassette ofFIG. 1.

FIG. 8 shows an example cassette like the cassette of FIG. 1, showingexample cabling extending from the input cable to the rear connectors ofthe adapter block.

FIG. 9 shows a second embodiment of a fiber optic cassette for receiptof LC connectors in a front of the adapter block.

FIG. 10 shows a third embodiment of a fiber optic cassette in accordancewith the present invention without the front adapter block.

FIG. 11 shows a further perspective view of the cassette of FIG. 10,with portions of the housing removed.

FIG. 12 is a top view of the cassette of FIG. 11.

FIG. 13 shows a fourth embodiment of a fiber optic cassette withportions of the housing removed.

FIG. 14 shows a further perspective view of the cassette of FIG. 13;

FIG. 15 shows the cassette of FIG. 13 in exploded view with the adapterblock separate from a remainder of the cassette housing;

FIG. 16 shows an exploded view of the adapter block with the splitsleeve and the rear connector removed from the adapter block.

FIG. 17 is an enlarged view a portion of the view of FIG. 16.

FIG. 18 is a cross-sectional view through one of the adapter ports ofthe cassette of FIG. 13;

FIG. 19 is a cross-sectional perspective view of the rear portion of thehousing of the cassette of FIG. 13;

FIG. 20 is a fifth embodiment of a fiber optic cassette in accordancewith the present invention, showing front ports sized for LC connectors,and also showing the use of attenuators in some of the ports.

FIG. 21 is a view of the cassette of FIG. 20, with portions of thehousing of the cassette removed;

FIG. 22 is an opposite side view of the cassette of FIG. 20, with acircuit board shown removed from the housing.

FIG. 23 is a first side view of the cassette of FIG. 20.

FIG. 24 is a second view of the cassette of FIG. 20.

FIG. 25 is a further side view of the cassette of FIG. 20 with portionsof the housing removed;

FIG. 26 is a front view of the cassette of FIG. 20;

FIG. 27 is a further side view of the cassette of FIG. 20.

FIG. 28 shows a cassette mounted for sliding movement relative to achassis.

FIG. 29 shows a cassette mounted in a housing.

FIG. 30 shows another view of the cassette and housing of FIG. 29 withportions of the housing removed.

FIG. 31 shows the housing of FIGS. 29 and 30 mounted vertically andhorizontally in different portions of the chassis.

FIG. 32 shows a cassette mounted on another housing.

FIG. 33 shows the housing of FIG. 32 mounted in a chassis.

FIG. 34 shows a cassette mounted on another housing which is slidablymounted relative to a chassis.

FIGS. 35 and 36 show further views of the chassis of FIG. 34.

FIG. 37 shows two cassettes mounted to a spool for storage of one ormore input cables.

FIG. 38 shows in cross-section an example adapter holding a mediareading interface.

DETAILED DESCRIPTION

In FIGS. 1-8, a first fiber optic cassette 10 is shown including a firstcable 12 connected to adapters or an adapter block 14 for receipt ofconnectors, such as LC or SC connectors at front ports 16. Cassette 10has a single cable 12 which includes multiple fibers 20 which terminateat a distal connector 22, such as an MPO style connector. Cable 12 canbe a variety of lengths such as one to 3 feet up to 50 to 100 feet, ormore.

Cassette 10 includes a body 26 defining a front 28, a rear 30 and aninterior 32. Body 26 further includes a top 34, a bottom 36, and sides38, 40. Cassette body 26 defines a cable entry location 44 which in theillustrated embodiment is along rear 30. In the illustrated embodiment,cable 12 includes an outer jacket 50 and inner strength member 52 aroundinner fibers 20. Fibers 20 extend past an end of jacket 50, and an endof strength member 52, and into interior 32 for connection with thefront connectors at adapters 14. As shown, cable 12 includes a boot 60to provide strain relief at cable entry location 44. Cable 12 can flexaway from cassette body 26 in the direction of arrow A, and is protectedfrom excessive bending by boot 60. Entry 44 is located close to corner42, so that boot 60 and cable 12 is partially protected at entry 44 bybeing able to reside in a rear channel 46. Adapters 14 are arrangedlinearly and positioned along longitudinal axis 62. Cable 12 at cableentry location 44 extends parallel to the longitudinal axis 62, althoughsome bending is permitted relative to the longitudinal axis 62.

In general, cassette 10 includes top 34 and bottom 36 which aregenerally parallel to each other and define the major surfaces ofcassette body 26. Sides 38, 40, front 28, and rear 30 define the minorsides of cassette body 26. The cassette can be oriented in any position,so that the top and bottom surfaces can be reversed, or positionedvertically, or at some other orientation.

As will be described below, multiple rows of adapters 14 can be providedwith cassette 10. See FIG. 32. In the illustrated embodiment, adapters14 are sized to receive front SC connectors. LC connectors can be usedwith appropriate sized adapters. See FIGS. 9, 20, and 32.

Cable 12 is connected to cable entry location 44 with a crimp tube 70and a crimp ring 72 which crimps jacket 50 and strength member 52 tocrimp tube 70. A small pocket 76 captures crimp tube 70 for retentionwith cassette body 26. Pocket captures hex end 78 of crimp tube 70 toretain cable 12 with cassette body 26.

Disposed within interior 32 of cassette body 26 are a plurality ofradius limiters 80 which provide cable bend radius protection for thefibers disposed within interior 32. Cable radius limiters 80 can be inthe form of discrete interior structures, and/or curved exteriorsurfaces which form around the front 28, rear 30, and sides 38, 40.

In the illustrated embodiment, the adapters 14 are formed in a blockconstruction 90 having a front end 92, and an opposite rear end 94.Front end 92 includes a profile for receiving SC connectors 108. Frontend 92 includes SC clips 96 for clipping to an SC connector. Adapterblock 90 also includes a rear clip 98 which clips to a hub and ferrule100 (hub 104 mounted to ferrule 106) which terminates each fiber 20exposed within interior 32 of cassette 10. Hub and ferrule 100 form arear connector. A split sleeve 102 is also provided for ferrulealignment between hub and ferrule 100 (rear connector) and the ferruleof the front SC connector 108. As shown in FIG. 8, fibers 20 areprovided with excess length between crimp tube 70, and the rearconnector defined by the termination at hub and ferrule 100. Severebending of the fibers is to be avoided. In the illustrated embodiment,the small size of the cassette 10 requires that some fibers 20 reversedirection via limiters 80.

Referring now to FIG. 9, cassette 110 is constructed in a similar manneras cassette 100 except that the adapters 114 are sized to receive LCconnectors at front 128. The hub and ferrule is made correspondinglysmaller to accommodate the LC front connectors. Adapters 114 arepreferably formed as a block 120.

In FIGS. 1-9, blocks 90, 120 are snap fit or otherwise attached to arest of body 26. A cover 48 covers a rear area behind blocks 90, 120.The cassettes 10, 110 can be sealed or they can be openable, so as toallow repair, or cleaning of the inner hub and ferrule 100. In somecases, blocks 90, 120 can be snap fit to a rest of the housing 26 forease of assembly. Blocks 90, 120 can also preferably be removed from arest of the cassette 10, 110 to allow for cleaning of the innerconnector. The inner fiber slack allows for blocks 90, 120 to be pulleda short distance away from the rest of the cassette 10, 110.

FIGS. 10-12 show a third embodiment of a fiber optic cassette inaccordance with the present invention without the front adapter block.Front clips 220 are used to clip to the adapter blocks 90, 120, andengage projecting posts on the blocks.

Another embodiment of a fiber optic cassette 310 is shown in FIGS.13-19. Cassette 310 includes a cable 12, a boot 60 and a cable entrylocation 344 in a similar location as cassettes 10, 110, 210. Cassette310 includes a removable adapter block 320, separatable from the rest ofbody 326. Once removed, module 320 allows rear hub and ferrule 100 to beremoved in a similar manner as in cassettes 10, 110, 210. Rear clip 98includes two clip members 330 which clip onto hub and ferrule 100. Torelease, tabs 332 are pressed together which causes an outward pivot ofclip members 330 about pivot members 334, thereby allowing removal ofhub and ferrule 100 for cleaning. Split sleeve 102 may be retained onferrule 106 during the removal process, and would need to be removed toclean the ferrule tip.

Cassette 310 also includes a pocket 338 for slack storage of fibers.Pocket 338 is formed with rounded outer surfaces 338 in body 326, androunded outer surfaces 350 in adapter block 320. Tabs 360 helpfacilitate positioning of the fiber storage loops in pocket 338, duringassembly and later removal of block 320, by directing the loopsdownward.

Referring now to FIGS. 20-27, a further alternative embodiment of acassette 410 is shown. One difference between the cassette 310 of FIGS.13-19 and cassette 410 is that an interior of the adapter blocks 420 aresized to receive traditional connectors such as SC or LC. In the exampleembodiment, the adapters are sized to receive LC connectors 408. In thisembodiment of a fiber optic cassette, front ports 416 are sized for LCconnectors, and show the use of attenuators 450 (with dust caps 460) insome of the ports 416.

Referring now to FIG. 28, cassette 10 is shown mounted in a chassis forrelative movement to the chassis along a sliding direction for access.For comparison, cassette 10 includes a single input cable which connectsto a rear MPO panel 480. Similar high-density distribution frames orblocks are described in U.S. Pat. No. 6,591,051, the disclosure of whichis incorporated by reference. It should be noted that the cassettesdescribed herein may be used in a sliding packs in a telecommunicationsrack such as that described in U.S. Pat. No. 6,591,051, incorporatedherein by reference in its entirety, or in other drawers and fixtures.Sliding adapter packs 150 such as shown in FIG. 28 are shown with aplurality of individual fibers extending to a fanout 430 which then hasa cable 450 that leads to MPO panel 480. Cassettes 10 allow for onlysingle cable 12 to be handled, saving space and installation time.

Referring now to FIGS. 29-31, cassette 10 is shown mounted to a housing500, wherein the housing is received in a chassis 530. FIG. 31 shows thehousing 500 of FIGS. 29 and 30 mounted vertically and horizontally indifferent portions of the chassis 530. Preferably, housing 500 isslideably movable to access a selected cassette 10.

Referring now to FIGS. 32 and 33, an alternative embodiment of acassette 610 is mounted to a further housing 600 which is received in achassis 630. Cassette 610 includes two rows of front adapters sized forLC connectors. Referring now to FIGS. 34-36, cassettes 110 are shownmounted to a horizontal tray 700 which is slideably received in achassis 730.

FIG. 37 shows two cassettes 810 mounted on opposite sides of a spool 820for storage of the input cable. Together the cassettes 810 and spool 820form a self contained termination and slack storage unit that can bemounted to a rack, frame, cabinet, drawer, fiber trough, or otherdevice.

In one embodiment, cassette 10 generally has a length of 3 to 4 inches(parallel to the longitudinal direction 62), a width of 2 to 3 inches(front to back), and a height of approximately ½ inch. More preferably,the length is 3 to 3½ inches, the width is 2 to 2½ inches, and theheight is ½ inch. The height can vary as needed, such as to accommodatemultiple rows of adapters. With such a construction, it is preferredthat the cable enter at the rear of the housing with a strain reliefboot and crimp parallel to the front, and that the internal cablesinclude managed slack such as with curved internal surfaces in order toavoid going below the minimum bend radius.

In accordance with some aspects, certain types of adapters 900 may beconfigured to collect physical layer information from one or more fiberoptic connectors 920 received thereat. For example, as shown in FIG. 38,certain types of adapters 900 may include a body 1000 configured to holdone or more media reading interfaces 1020 that are configured to engagememory contacts on the fiber optic connectors 920. One or more mediareading interfaces 1020 may be positioned in the adapter body 1000. Incertain implementations, the adapter body 1000 defines slots 1010extending between an exterior of the adapter body 1000 and an internalpassage in which the ferrules of the connectors 920 are received.

Certain types of media reading interfaces 1020 include one or morecontact members 1021 that are positioned in the slots 1010. As shown inFIG. 38, a portion of each contact member 1021 extends into a respectiveone of the passages to engage memory contacts on a fiber optic connector920. Another portion of each contact member 1021 also extends out of theslot 1010 to contact a circuit board 1030. Portions of the cassette maydefine conductive paths that are configured to connect the media readinginterfaces 1020 of the adapter 900 with a master circuit board. Themaster circuit board may include or connect (e.g., over a network) to aprocessing unit that is configured to manage physical layer informationobtained by the media reading interfaces. See also cassette 410 of FIGS.20-27.

Example adapters having media reading interfaces and example fiber opticconnectors having suitable memory storage and memory contacts are shownin U.S. application Ser. No. 13/025,841, filed Feb. 11, 2011, titled“Managed Fiber

Connectivity Systems,” the disclosure of which is hereby incorporatedherein by reference.

In addition to the various uses and applications of the describedcassettes, the cassettes can be used to terminate the fibers of amulti-fiber FOT cable, such as a 144 fiber cable, to make installationof the terminated cables easier and faster. Also, the cassette can beassociated with a cable spool such as disclosed in US2011/0222829 orUS2011/0044599, the disclosure of which is hereby incorporated herein byreference.

One advantage of the disclosed cassettes is that handling in the fieldof individual connectors is eliminated or MPO connectors and fanoutswith upjackets are eliminated.

Claims:
 1. A fiber optic cassette comprising: a body defining a frontand an opposite rear and an enclosed interior; a cable entry locationdefined in the body for a cable to enter the interior of the cassette,wherein a cable that enters at the cable entry location is attached tothe cassette body and fibers are extended into the cassette body andform terminations at connectors; wherein the connectors are connected toadapters located at the front of the cassette; wherein a front side ofthe adapters define termination locations for cables to be connected tothe fibers connected at the rear of the adapters wherein the cableincludes a jacket, a strength member, and fibers, wherein the strengthmember is crimped to a crimp tube and is mounted to the cassette body,allowing the fibers to extend past the crimp tube into the interior ofthe cassette body, and wherein a strain relief boot is provided at thecable entry location.
 2. The cassette of claim 1, wherein the cableentry location is located at the rear of the cassette body opposite tothe front.
 3. The cassette of claim 1, wherein the cassette body definesa top surface and a bottom surface which define major sides of thecassette body and extend between the front and the rear, wherein theadapters along the front are arranged linearly and extend in alongitudinal direction parallel to the major surfaces defined by the topand the bottom of the cassette body.
 4. The cassette of claim 3, whereinthe cable at the cable entry location extends parallel to thelongitudinal direction before entry into the cassette body.
 5. Thecassette of claim 1, further comprising cable radius limiters whichprovide cable management of the fibers extending from the cable entrylocation to the connectors at the rear of the adapters.
 6. The cassetteof claim 1, wherein the adapters are in the form of an adapter blockwith a plurality of adapters and include a front end, a rear end, andinternal structures which allow mating with fiber optic connectors atthe front end.
 7. The cassette of claim 6, wherein each of the pluralityof adapters are configured to receive SC format fiber optic connectorsat the front end.
 8. The cassette of claim 6, wherein each of theplurality of adapters are configured to receive LC format fiber opticconnectors at the front end.
 9. The cassette of claim 6, wherein theadapter block is removable from a remainder of the cassette.
 10. Thecassette of claim 1, wherein a rear of the adapter block defines a rearclip which retains a split sleeve and a hub and ferrule of a connectorwhich terminates an interior fiber.
 11. The cassette of claim 1, whereinthe rear end of the adapter block defines an opening for receipt of anSC or LC style connector.
 12. The cassette of claim 1, wherein thecassette can be utilized in a chassis which includes a stationary mountrelative to the chassis, or the cassette can be movably mounted, such asin a variety of sliding movements to allow access to a selectedcassette, thereby improving access to a selected front connectorattached to the cassette.
 13. A fiber optic cassette comprising: a bodydefining a front and an opposite rear and an enclosed interior, the bodyfurther defining a top surface and a bottom surface which define majorsides of the cassette body and extend between the front and the rear; acable entry location defined in the body for a cable to enter theinterior of the cassette, wherein a cable that enters at the cable entrylocation is coupled to the cassette body and fibers are extended intothe cassette body and form terminations at first connectors; wherein thefirst connectors are connected to a rear side of adapters of an adapterblock located at the front of the cassette, each of the first connectorsincluding a hub and ferrule and a split sleeve; wherein a front side ofthe adapters define termination locations for cables to be connected tothe fibers connected at the rear side of the adapters, the terminationlocations configured to receive second fiber optic connectors having adifferent configuration than the first connectors; and wherein theadapters along the front of the cassette body are arranged linearly andextend in a longitudinal direction parallel to the major surfacesdefined by the top and the bottom of the cassette body.
 14. The cassetteof claim 13, wherein each of the plurality of adapters are configured toreceive LC format fiber optic connectors at the front side.
 15. Thecassette of claim 13, wherein each of the plurality of adapters areconfigured to receive SC format fiber optic connectors at the frontside.
 16. The cassette of claim 13, wherein the cable entry location islocated at the rear of the cassette body opposite to the front.
 17. Thecassette of claim 13, wherein the adapter block is removable from aremainder of the cassette.
 18. The cassette of claim 13, wherein thecable at the cable entry location extends parallel to the longitudinaldirection before entry into the cassette body.
 19. The cassette of claim13, further comprising cable radius limiters which provide cablemanagement of the fibers extending from the cable entry location to thefirst connectors at the rear side of the adapters.
 20. The cassette ofclaim 13, wherein the cassette can be utilized in a chassis whichincludes a stationary mount relative to the chassis, or the cassette canbe movably mounted, such as in a variety of sliding movements to allowaccess to a selected cassette, thereby improving access to a selectedsecond fiber optic connector attached to the cassette.